Dual color IR detection modules, trends and applications
Zwei-Farben IR-Detektoren, Trends und Anwendungen
The 3rd generation of infrared (IR) detection modules is expected to provide advanced features like higher resolution 1024x1024 or 1280x720 pixels and/or new functions like multicolor or multi band capability, higher frame rates and better thermal resolution. This paper is intended to present the current status and trends at AIM on antimonide type II superlattices (SL) dual color detection module developments for ground and airborne applications in the high performance range, where rapidly changing scenes - like e.g. in case of missile warning applications for airborne platforms or ground based sniper detection systems - require temporal signal coincidence with integration times of typically 1ms. AIM and IAF selected antimonide based type II superlattices (SL) for such kind of applications. The type II SL technology provides - similar to QWIP's - an accurate engineering of sensitive layers by MBE with very good homogeneity and yield. IAF and AIM managed already to realize a dual color 384x288 IR module based on this technology. It combines spectral selective detection in the 3 - 4&mgr;m wavelength range and 4 - 5 &mgr;m wavelength range in each pixel with coincident integration in a 384x288x2 format and 40x40 &mgr;m2 pitch. Excellent thermal resolution with NETD < 12 mK @ F/2, 2.8 ms for the longer wavelength range (red band) and NETD < 22 mK @ F/2, 2.8 ms for the shorter wavelength range (blue band) were reported. In the meantime a square design of 256x256x2 pixel with a reduced pitch of 30x30 &mgr;m2 is in preparation. In this case with 2 Indium bumps per pixel and a third common contact for all pixels required for temporal coincidence is connected at the outer area of the array. The fill factor is approx. 65% for both wavelength ranges. The reduced size of the array enables the use of a smaller dewar with reduced cooling power and significantly reduced weight and broadens the scope of applications where weight and costs is essential. Design aspects and expected performances are discussed.